Grep and find

Searching inside files with grep (4 min)

Finding files with find (5 min)

Combining find and grep (4 min)

In its simplest usage, xargs command lets you construct a list of arguments:

find . -name "*.txt"                   # returns multiple lines
find . -name "*.txt" | xargs           # use those lines to construct a list
find . -name "*.txt" | xargs command   # pass this list as arguments to `command`
command $(find . -name "*.txt")        # command substitution, achieving the same result (this is riskier!)
command `(find . -name "*.txt")`       # alternative syntax for command substitution

In these examples, xargs achieves the same result as command substitution, but it is safer in terms of memory usage and the length of lists you can pass.

Where would you use this? Well, consider grep command that takes a search stream (and not a list of files) as its standard input:

cat filename | grep pattern

To pass a list of files to grep, you can use xargs that takes that list from its standard input and converts it into a list of arguments that is then passed to grep:

find . -name "*.txt" | xargs grep pattern   # search for `pattern` inside all those files (`grep` does not take a list of files as standard input)